Installation (computer programs)

Installation (or setup) of a computer program (including device drivers and plugins), is the act of making the program ready for execution. Because the process varies for each program and each computer, programs (including operating systems) often come with an installer, a specialized program responsible for doing whatever is needed for their installation. Installation may be part of a larger software deployment process.

Installation typically involves code being copied/generated from the installation files to new files on the local computer for easier access by the operating system. Because code is generally copied/generated in multiple locations, uninstallation usually involves more than just erasing the program folder. For example, registry files and other system code may need to be modified or deleted for a complete uninstallation.

Overview

Some computer programs can be executed by simply copying them into a folder stored on a computer and executing them. Other programs are supplied in a form unsuitable for immediate execution and therefore need an installation procedure. Once installed, the program can be executed again and again, without the need to reinstall before each execution.

Installer (OS X)

Installer is an application included in OS X (and in its progenitors OPENSTEP and NeXTSTEP) that extracts and installs files out of .pkg packages. It was created by NeXT, and is now maintained by Apple Inc. Its purpose is to help software developers create uniform software installers.

Installer resides at /Applications/Utilities/Installer.app on Macintosh computers running OS X versions prior to 10.5, and launches when a package or metapackage file is opened. In OS X Yosemite, the Installer application is located at /System/Library/CoreServices/Installer.app. The installation process itself can vary substantially, as Installer allows developers to customize the information the user is presented with. For example, it can be made to display a custom welcome message, software license and readme. Installer also handles authentication, checks that packages are valid before installing them, and allows developers to run custom scripts at several points during the installation process.